//
// Created by ✎﹏ℳ๓独赏 ☆独醉 on 2023/3/20.
#include <stdio.h>
int binsearch(int x,int *v,int n){
    int left=0,right=n,mid;
    while (left<=right){
        mid =(left+right)/2;
        if(x>v[mid]){
            left=mid+1;
        }else if(x<v[mid]){
            right=mid-1;
        }else{
            printf("x=arr[%d]",mid);
        }
    }
    if(left>right){
        printf("Not Found");
    }
}
int main(){
    int i,x,n=49,arr[50];
    for(i=0;i<n;i++){
        arr[i]=i;
    }
    scanf("%d",&x);
    binsearch(x,arr,n);
    return 0;
}